Due to continual progress of the science and technology, computers have become popular in everyday lives of people. Computers are constantly updated and improved to meet the requirements of software in a general trend towards multimedia. Common clients, however, can't afford the constantly updated computers. Therefore, a user usually replaces the motherboard and the microprocessor in a computer to update a computer and enhance the functions thereof.
As shown in FIG. 1, in a conventional computer motherboard 1, a microprocessor 12 is connected to a pulse width modulation (PWM) control unit 14, and sends a voltage correspondence signal required for work to the PWM control unit 14. After the PWM control unit 14 receives the voltage correspondence signal from the microprocessor 12, it generates a PWM signal corresponding to the voltage required for work of the microprocessor 12 for controlling a drive unit 16 to drive at least a power switch 18 for performing switching actions according to power provided by the motherboard 1, thereby outputting the voltage required for work of the microprocessor 12.
Reference is made to FIG. 1 again. A user usually upgrades a computer with a faster microprocessor 12. The working voltage specification of the new microprocessor 12, however, is generally different from that of the old microprocessor 12. Therefore, when the new microprocessor 12 sends the voltage correspondence signal required for work to the PWM control unit 14, the PWM control unit 14 can't produce a PWM signal corresponding to the voltage required for work of the new microprocessor. The PWM control unit 14 thus can't accurately control the drive unit 16 to drive the power switch 18 for performing switching actions, and hence is not able to output the voltage required for work of the new microprocessor 12.
The new microprocessor 12 is not compatible with the PWM control unit 14 on the original motherboard 1. That is, the PWM control unit 14 on the original motherboard 1 can't provide the working voltage for normal operations of the new microprocessor 12. Therefore, when a user installs a new microprocessor 12, it is usually necessary for him to also install a new computer motherboard 1 to provide the voltage required for work of the new microprocessor 12. In other words, the upgrade is expensive.